Component:

'iso-manager', 'upgrade'

Why this is needed:

When doing an upgrade the first step is to mount the new metalk8s.iso using the iso-manager script using the following command: /srv/scality/metalk8s-X.X.X/iso-manager.sh -a <path_to_iso>.
One may use a relative path for the metalk8s.iso, which can lead to a situation where the boostrap.yaml file is updated with an invalid archive entry. (cf #3079). The solution script (which is doing something similar when importing a solution) is computing the absolute path from what is provided by the user.

What should be done:

As for the solution script, the iso-manager script should check and compute the absolute path for the metalk8s.iso arg that is passed by the administrator and store it as an absolute path in the boostrap.yaml file

Implementation proposal (strongly recommended):

Test plan: